From the consumer's point of view, textiles made of cellulose, such as cotton or regenerated cellulose fibers (for example, modal or lyocell), have positive characteristics in respect of wear comfort. However, a big disadvantage of these textiles is that these textiles easily wrinkle while worn, after washing and drying. This wrinkling tendency is based on the swelling of the cellulose fibers and the low elastic restoring forces (“resilience”) of the cellulose fibers after deformation.
Therefore, it has long been common that, after washing and drying, cotton textiles or cellulosic textiles are ironed and thereby brought into the desired shape. However, it would be advantageous for the consumer if the consumer could reduce the formation wrinkles as part of the textile care, which would make the work of ironing easier or, ideally, make ironing completely unnecessary.
In the production of textiles, an attempt is made to avoid the wrinkling tendency of the cellulose molecules by means of permanent textile finishing processes by cross-linking the cellulose molecules. The cross-linking of the cellulose molecules increases the elasticity of the material. The wrinkling-avoiding finishing processes are performed on the gray goods as part of the textile finishing. However, cross-linking agents that are used in the textile industry, such as formaldehyde-urea and formaldehyde-melamine combinations, are not suitable for use in washing agents or for use in the home because of the toxicity of said cross-linking agents or because of the conditions under which said cross-linking agents must be used.
Formaldehyde-free cross-linking methods for cellulose are also known, such as a cross-linking method known from U.S. 20040043915 A1, which is performed by means of hydroxy-group-bearing polymer and polycarboxylic acids, particularly butanetetracarboxylic acid (BTCA). The use of tetracarboxylic acids to cross-link cellulose fibers is known from the article by C. M. Welch in Textile Research Journal, 1988, 480-486. In principle, these formaldehyde-free approaches to cellulose cross-linking by means of polycarboxylic acids could be suitable for use in the home from a toxicological perspective. Unfortunately, the reactions of the carboxyl groups of polycarboxylic acids with the hydroxyl groups of the cellulose, which lead to esters, require a large amount of catalysts such as triazoles or hypophosphites or phosphites and high temperatures. This is not practical for an end-consumer product.
In another approach, as described for example by M. Hashem, P. Hauser, and B. Smith in Textile Research Journal, 2003, 762-766, ion pair bonds are used to cross-link the cellulose. Cotton typically has a content of carboxyl groups of approximately 10−6 mol/g. To achieve the most ion pair contacts possible, the cellulose can be treated with chloroacetic or bromoacetic acid to increase the number of carboxyl groups of the cellulose. Because of the interaction of the carboxylated cellulose with polycations such as cationized chitosan, ionic cross-linking can arise, which reduces the wrinkling tendency. The effect is too small without the carboxylation, and the carboxylation of cotton textiles with haloacetic acids is out of the question for home use.
From the patent application CN 1793483 A, a method for producing modified cotton fibers is known, which comprises the steps of oxidizing bleached cotton fibers with periodate, removing the oxidant, washing and drying the cellulose fibers, and cross-linking by reaction with a substance containing OH and NH2 groups, such as collagen, chitosan, silk fibroin, or sericin.
Accordingly, it is desirable to have an improved agent suitable for treating cotton or cellulosic textiles at home in order to reduce the wrinkling tendency of the textiles and also make the textiles easier to iron. In addition, it is desirable to have an improved method, adapted to be performed at home, for treating textiles made of cellulose-containing material in such a way that ironing is made easier and/or the wrinkling tendency is reduced. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with this background of the invention.